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Perspective Growth, and Death Of Microorganisms

This article explores the fascinating history and growth of microorganisms, particularly bacteria, that have existed for billions of years alongside human evolution. It emphasizes the critical role these organisms play in our ecosystems and the importance of understanding their growth behavior for food safety. Professor Thomas J. Montville discusses the implications of microbial presence in food, the potential for foodborne illnesses, and the importance of proper food handling practices to ensure safety from farm to fork.

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Perspective Growth, and Death Of Microorganisms

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  1. Perspective Growth, and Death Of Microorganisms Professor Thomas J. Montville

  2. Respecting our Ancestors • Earth formed 6 billion years ago • Bacteria appear 3.5 billion years. • Dinosaurs go extinct 250 million years ago. • Humans arrive 3 million years ago. • Take home message:________________

  3. Take home message:________________

  4. Bacteria ‘R Us • Bacteria are the most predominant life form, by number and mass. • (Take home: _______) • You are as many bacterial cells as human cells. • You are an open ecosystems.

  5. “We do not live in a sterile world.” “There’s nothing we can do to keep a bird from pooping on that field.” Dr. Tom Montville, News Channel 4

  6. Food Safety - Old Model • Pinpoint Problem • Provide Solution • Promulgate Regulation • Punish

  7. Food Safety -Reality • Place Event Result • Farm Lettuce near pig pen 60 E.coli O157:H7 • Truck Pasteurized after raw 30,000 salmonellosis • Factory Pasteurize half of input-100 listeriosis • Outlet Undercook product E.coli O157:H7 outbreak • Home Wrong storage Temp. Botulism Who is responsible for food safety? _______________

  8. Food Safety Farm to Fork

  9. * * Tauxe, 2005. (2005 data in MMWR of April 14, 2006 are similar. )

  10. Questions and Answers:

  11. Modes of Microbial Growth Bacteria: Molds: Yeast:

  12. The bacterial growth cycle has four phases: 12 stationary death 8 log cfu/ml logarithmic or exponential 4 lag time

  13. The Miracle (or curse) of Exponential Growth N = Noekt N = Number of bacteria at any time, t No= Initial number of bacteria k= Rate constant, influenced strongly by temperature, also influenced by environmental conditions

  14. In plain English, bacteria grow by doubling: • 1 -> 2 -> 4 -> 8 -> 16 -> 32 -> 64 -> 128 -> 256 => 500 -> 1000 -> • One bacterium can grow to one million bacteria • in ___ doublings!

  15. Handwashing reduces No(http://users.aol.com/comcontrol/comply.htm) (http://www.asmusa.org/pcsrc/ochsur.htm) • Study of handwashing in restaurants, foodservice, healthcare settings show <2 washings per day. • FDA estimates poor handwashing contributes to 80 million cases in U.S. • 94 % say they wash their hands after using public toilets. • 68% observed wash their hands after using public toilets.

  16. Bacteriological Survey of Sponges and Dishcloths (Enriquez, et al., 1997. Dairy Food Environ Sanitarian 17:20-24)

  17. Restaurants, Bars, and HomesYepiz-Gomez, et al. J. Food Protect. Trends. 26:786-792, 2006

  18. The ultimate comparison, Restaurants vs Homes!

  19. “Reasonable” Microbiological Criteria for Ready to Eat Foods • Salmonella 0/25 g • Listeria monocytogenes 0/25g • E. coli <10 cfu/g • O157:H7 “none” • Staphylococcus aureus <100 cfu/g • Clostridium perfringens <100 cfu/g • “Total” plate count <500,000 cfu/g

  20. Influence of temperature 1200 1000 Doubling time, min. 800 600 400 330 200 155 20 0 10 20 30 40 Temperature, °C

  21. Temperature effect on growth- chicken 10° C 4.4° C 0° C 12 slime 8 odor log cfu/cm2 4 2 4 8 16 time, days

  22. THE "40-140" RULE • FOODS SHOULD BE HELD: • BELOW 40° F • OR • ABOVE 140°F • COROLLARY: • WHEN HEATING OR COOLING, BRING FOODS THROUGH THE 40-140°F REGIONAS RAPIDLY AS POSSIBLE

  23. Microbial death curve, Ideal 12 8 log cfu/ml 4 0 time

  24. IMPLICATIONS OF LOGARITHMIC DEATH: • 1) Sterility is theoretically impossible. • 2) The effectiveness of a given heat treatment is dependent on the initial microbial load, i.e. a 6D process that "works" when the initial number is 104 cfu/ml will 'fail' when the initial number is 108 cfu/ml. • 3) The significance of 'fractional survivors.' In a 6D process, if you start with 1 spore per unit, one in 106 units will contain a viable spore after processing.

  25. “The perp walk”

  26. Sporulation and Germination sporulation vegetative cell dormancy activation germination outgrowth

  27. Botulism and Temperature Abused Pot Pie (Morbidity and Mortality Weekly Report, Vol. 32, # 3, January 1983). • Patient: 56 year old diabetic woman • Symptoms: diplopia, weakness, difficulty breathing, chest pain, respiratory arrest. • Scenario: Son prepared pot pie for mother. Father brought home take-out hamburgers. Mother left pot pie out on shelf (in California, in August), and ate it two and one-half days later without reheating. • Illness: next day. Type A botulinum toxin was isolated from the left-over food and patient's serum.

  28. Diarrheal type Onset: > 6 hr Range = 6 - 14 hr Average = 9 hr Symptoms: Diarrhea Nausea, Cramps Rectal tenesmus Fever generally absent Recovery: 20 - 36 HR Emetic type Onset: < 6 hr Range = 0.5 - 6 Hr Average = 2 hr Symptoms: Vomiting, Nausea, Cramps Diarrhea (+) Fever generally absent Recovery: 8 - 10 Hr Bacillus cereus - food poisoning

  29. Foods associated with Bacillus cereus outbreaks • Meats and Gravies • Sauces and Puddings • Miscellaneous Vegetable Dishes • Fried Rice and Other Rice Products

  30. Many Bacillus thuringiensis isolates produce "Bacillus cereus" diarrheal toxin. S.G. Jackson, et al., 1995. Letters Appl. Microbiol. 21:103-105. P.H. Damgaard, et al., 1996. Letters Appl. Microbiol. 23:146-150.

  31. Staphylococcus aureus • FOOD POISONING SYNDROME • onset: 0.5 to 6 hours • recovery: 24 to 72 hrs • major symptoms: vomiting, diarrhea • other symptoms: nausea, salivation, • cramps, retching, • prostration

  32. Staphylococcus aureus Case Study • Flight from Tokyo to Copenhagen via Anchorage • 196 of 343 passengers, 1 of 20 crew • food eaten: • 1 h post Anchorage, snack, served to all • 5.5 h post Anchorage, steak dinner, crew • 5.6 h post Anchorage, cheese omelet w/ ham • passengers only • onset: 0.5 to 5.5 h after breakfast, average 2.5 h • symptoms: • diarrhea (88%), vomiting (82%) • cramps (74%), nausea (68%)

  33. Staphylococcus aureus Investigation • Isolated SED-producing S. aureus from fecal swabs of 5 patients and from left over omelet and ham. • Isolated SED from omelet and ham. • Breakfast prepared day before flight, held at room temperature for 6 h during preparation • Held 14.5 h at 10°C prior to the flight. • Held at room temperature during the flight, then heated. • Isolated SED-producing S. aureus from inflamed lesion on the hand of the cook who had made the breakfast.

  34. 1989- STAPHYLOCOCCAL FOOD POISONING • Staphylococcal Enterotoxin Found • In Canned Mushrooms From • Peoples Republic of China • 4 Outbreaks, > 100 Cases • English, et al., Dec. 1990, Food Technol. p. 74

  35. centralized agriculture: • local farm plant export • 2 to 4 hours • free market agriculture: • local farm brokers plant export • weeks in PVC bags • S. aureus is poor competitor with aerobic • spoilage organisms, but competes well under • anaerobic conditions. • O2 respiratory demand = 3,160 cc/kg/h • PVC permeability = 21 cc/h

  36. centralized agriculture: • local farm plant export • 2 to 4 hours • free market agriculture: • local farm brokers plant export • weeks in PVC bags • S. aureus is poor competitor with aerobic • spoilage organisms, but competes well under • anaerobic conditions. • O2 respiratory demand = 3,160 cc/kg/h • PVC permeability = 21 cc/h

  37. Why do "new" pathogens emerge?(Lynton Cox, Food Technol. 43(12)52-59, 1989) • 1. CHANGES IN EATING HABITS, fresh, organic • 2. CHANGES IN AWARENESS , computer databases • 3. CHANGES IN DEMOGRAPHICS • larger sensitive populations • 4. CHANGES IN PRIMARY FOOD PRODUCTION • scale of operation, global production • 5. CHANGES IN FOOD PROCESSING TECHNOLOGY. MA, chill, vacuum packaging • 6. CHANGES IN HANDLING AND PREPARATION • home refrigeration, microwave • 7. CHANGES IN THE MICROORGANISMS, plasmids

  38. Bad News on Refrigeration • Hutton, et al., 1991, J Food Safety 11:255-267 • 15 CITY - 100 SUPERMARKET STUDY OF REFRIGERATOR CASES • 90% OVER 40°F • 20% OVER 50°F • Woodburn, J. Am. Diet. Assoc. 87:322-326 • 21% OF HOME REFRIGERATORS OVER 50°F

  39. Listeria monocytogenes-disease syndromes • 1. Low grade "flu-like" infection - not serious, except in pregnant woman (who abort). • Up to 16% women carry L. monocytogenes without illness. (Larmont and Postlethwaite, 1986, J. Infection 13:187-193.) • 2. Listeric meningitis- headache, drowsiness, coma. 50% fatality rate. If very young and old are excluded, this drops to 30%. • 3. Perinatal infection - 0.15% to 2.0% of all perinatal mortality. • 4. Encephalitis • 5. Psychosis • 6. Infectious mononucleosis • 7. Septicemia

  40. Los Angeles Mexican Soft Cheese • - 93 Perinatal cases: • 19 Still births • 10 Postnatal deaths • - 49 Adult cases: • 18 Deaths • - Linked with Mexican soft cheese • - Same phage type isolated from cases • and processing plant • - Plant's milk throughput • exceeded capacity of pasteurizer • - Cheese was alkaline phosphate positive

  41. Sporadic ListeriosisSchwartz, et al., 1988, Lancet 779-782 • CDC population study of 34 million people yields 154 cases with 28%fatality. • 82 cases matched with 239 controls reveals statistical link to uncooked hot dogs, undercooked chicken. • Home refrigerator study

  42. General Population Over 70 years old Pregnant H.I.V. positive 0.7 cases /100,000 3 times higher 17 times higher 100 - 300 times higher Risk for ListeriosisSouthwick & Purich, New Eng. J. Med. 334:770, 1996

  43. There is a zero tolerance for L. monocytogenes in r-t-e foods, but no 100% accurate for detecting it.

  44. 1998/99 “Sara Lee” Outbreak • (Bil Mar, Ball Park franks) • 79 illnesses in 17 states • 12 deaths, three miscarages • 35 million pounds of product recalled • Recall costs (to Sara Lee) $50-70 million • Stock price falls from $55 to $25 • Oscar Mayer (Unit of Philip Morris) also has January recall of deli meats due to illness report • These are the “big boys,” • what of the “mom & pops”?

  45. Salmonella

  46. Salmonella spp. • Increasing antimicrobial resistance. • Large and dispersed outbreaks. • Habitat intestinal tract of animals. • 49% of animal feed contaminated. • 15-25% of poultry contaminated.

  47. S. enteritidis • Colonizes ovaries. • Internal contamination of egg. • May penetrate egg shell during cooling. • Capable of multiplication at 10-15 C in egg yolk or albumen. • Generally low numbers recovered. • Low % contaminated samples.

  48. S. enteritidis • Outbreak 1994, 224,000 persons in U.S. develop S. enteritidis gastroenteritis after they ate ice cream. • Contamination was linked to transport of pasteurized ice cream premix in tanker trailers that had previously carried nonpasteurized liquid eggs. • SOP violations: • British Airways Outbreak • Casino case

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